This invention relates to an exhaust pressure feedback system used in conjunction with an electronic fuel injection control circuit for an internal combustion engine of the type described in U.S. Pat. No. 4,280,465, issued July 28, 1981 and assigned to the same assignee as the instant invention. Reference is made to said United States Patent for greater descriptive detail of a control circuit for a fuel injected engine to which the present invention is illustratively applicable.
In fuel injection control circuits of the character indicated, certain engine parameters are monitored and utilized to control the fuel injectors supplying fuel to each cylinder of the internal combustion engine. The engine parameters being monitored included manifold absolute pressure, manifold temperature, throttle angle, and engine speed. The fuel injectors are in turn supplied by a fuel pump connected to an associated fuel tank with a pressure regulator associated with the fuel tank being used to maintain a constant pressure differential across the fuel injectors to insure even fuel flow.
Although fuel injection control circuits of the type described are widely used and have numerous advantages, such systems are relatively complex and expensive. In particular, the necessity to monitor manifold absolute pressure and utilize this parameter to control the fuel injectors, adds substantial cost to such a fuel injection control circuit. In particular, it is estimated that the transducer necessary to monitor absolute pressure along with its associated circuitry accounts for nearly fifty percent of the cost of a fuel injection control circuit of the type described.
It is, therefore, an object of the instant invention to provide a fuel injection control circuit less complex and less expensive than those described in the prior art.
It is a further object of the instant invention to provide an inexpensive fuel injection control circuit by eliminating the necessity to monitor manifold absolute pressure as a parameter for controlling the fuel injectors.
It is a general object of the instant invention to achieve the above objects with generally uncomplicated circuitry adaptable to the fuel mixture requirements of a variety of sizes and styles of different fuel injected internal combustion engines.